Generally, fluorescent lamps, which are economical and have high illumination intensity, have been used as lighting equipment in houses, buildings, factories and the like. A fluorescent lamp is a lighting device that operates in such a way that high voltage therein causes an electrical discharge and ultraviolet light generated therefrom reacts with fluorescent material painted on the inner side of the lamp, whereby visible light is emitted. Here, as a lighting system for a fluorescent lamp, there are a magnetic ballast lighting system using a magnetic ballast and a starter (a glow starter or a rapid starter) and an electronic ballast lighting system using an electronic ballast.
Fluorescent lamps are used as lighting devices for enabling products or articles exhibited or displayed in shopping malls, exhibition centers and the like to look vivid and beautiful, or as various forms of lighting devices for interior design, but they are problematic in that it is difficult to acquire desired brightness for a given amount of power consumption.
Recently, in order to solve this problem, the use of LED lamps, which operate at low voltage and have a long lifespan, low power consumption, fast response time, high resistance to shocks, and reduced size and weight, is increasing. Generally, an LED lamp is installed in the housing of a lamp, in which a fluorescent lamp has typically been installed. Here, the housing of the lamp includes a ballast therein.
However, if no protection circuit for preventing overcurrent and overvoltage is installed in the ballast in the light fixture, when a user installs an LED lamp, the user may contact the terminal of the LED lamp, which is connected with the ballast, whereby the user may be subjected to an electric shock. Specifically, if no protection circuit for preventing overcurrent and overcharge is included in the ballast, if any one of the terminals of one base of the LED lamp is connected to the ballast, the terminals of the opposite base of the LED lamp are shorted, and when the user touches the shorted terminals, the user may be subjected to an electric shock.
Also, in a certain LED lamp, a mechanical switch is installed in a terminal unit, and power is applied only when all terminals on both sides of the LED lamp are connected to the light fixture, whereby an electric shock is prevented. However, the LED lamp using a mechanical switch is problematic in that contact failure may occur depending on the degree of vibration and coupling, and thus power may not be stably supplied to the LED lamp.